This invention relates to an access gateway apparatus for controlling user access in a network system. More particularly, this invention relates to redundancy control and a session restoration method in an access gateway apparatus that includes a control access gateway apparatus (C-AGW apparatus) for mainly processing a control signal and a plurality of user access gateway apparatuses (U-AGW apparatuses) for mainly processing user packet transfer.
Popularization of broadband Internet services or third-generation mobile stations now enables a large number of users to use various services at any time of day. A carrier as a service provider has to build an access network system that may accommodate subscribers increasing in number year by year and deal with an increasing number of data access lines without any service stoppage. In a field of mobile wireless access communication, an increase in number of sessions and improvement of wireless communication band now require great improvement in throughput of the access gateway apparatus that accommodates wireless base stations (BSs). An exemplary access gateway apparatus is discussed in Sections 4.4 and 4.6 of “Basic IP Service for Converged Access Network Specification”, 3rd Generation Partnership Project 2, Dec. 19, 2007.